Process for separation of mineral oil



N 0 Drawing. I

Patented May 30, 1933 i UNITED STATES? PATENT OFFICE MALCOLM H. rtr'rrLE', or lvnw ROCHELLE, NEW YORK raocnss roa SEPARATION or .MINERAL OIL This invention relates to a process for the separation of mineral oil into fractions which are respectively more paraflinic in composition and characteristics and more naphthenic in composition and characteristics than is the original oil and which may have similar boiling ranges.

Mineral oils comprise naphthenic constituents and paraflinic constituents which have different characteristics that are known to a considerable extent; and these constituents impress their characteristics upon the oil to a degree depending upon the proportion in which they are present in the oil. Oils comprising a relatively higher proportion of' paraflinic constituents are commonly called parafiinic base oils, an example thereof being oils from the Pennsylvania field; and oils containing a relatively lower proportion of paraflinic constituents and therefore a relatively higher proportion of naphthenic constituents are commonly-called naphthenic or asphaltic base oils, an example of such oils being oils obtained from Gulf Coastal or Mexican fields; and oils containing an intermediate proportion of paraflinic constituents and also containing naphthenic constituents are commonly called mixed base oils, an example of such oils being oils from the mid-continent fields. Paraifinic oils having a given viscosity have a lower specific gravity, a. higher flash test, a smaller change of viscosity in changes in temperature and a higher ratio of hydrogen to carbon than do naphthenic oils of the same viscosity. Paraffinic oils are more stable and more desirable as lubricants, particularly under conditions involving high temperatures and extensive changes of temperature than are oils in which parafiinic constituents are present in relatively lower proportion and naphthenic constituents are present in relatively high proportion. The characteristics of mid-continent or mixed base oils are intermediate the characteristics of and asphalt base oils.

Naphthenic oils are preferable to parafi'inic oils for some uses, such as insulating oils for electrical apparatus and lubrication of chains and ofgearing not subjected to low temperatures. In other words, the effects of a high parafiin base Application filed December 22, 1932. Serial No. 648,382.

or increased proportion of paraflinic constituents of an oil are known and the uses in which such oils are preferable are known; and the characteristics imparted to oil by a high or increased proportion of naphthenic constituentsare' known, and the uses in which such oils arpreferable are known.

'An object of this invention is to provide a process whereby mineral oils may be rapidly and economically separated into fractions 6 which are respectively more parafiinic and more naphthenic than-the original oil, the separation being effected regardless of whether the oil has previously been subjected to acid treatment and without'chemical reaction and withoutformation of sludge, to the end that solvents employed to effect such separationmay be used indefinitely and losses minimized.

A specific object of this invention is to provide a method whereby oils obtained from mixed base petroleum may be separated into fractions of which at least one is a lubricating oil stock having viscosity-gravity characteristics and viscosity-temperature characteristics similar to or equal to or better than such characteristics of oil stocks having similar viscosity and obtained by usual distillation from crude oils from the Pennsylvania G 024- 0.022 log (V 35.5) 0.775

where d=viscosity-gravity constant V'=Saybolt viscosity at 210 F. G=specific gravity at 60 F.

tinent lubricating oils have a viscosity-gravity" constant falling between approximately .827 and .867; and naphthenic or asphalt base lubricating oils from the Gulf coast and California have a viscosity-gravity constant falling between approximately .867 and .887. However, specific oils from one field will have a viscosity-gravity constant falling within the range above given for another field. Moreover, the relation of temperature to viscosity is measured by a viscosity index in which Pennsylvania oils have a value of 90 to 100 and oils of lower viscosity index are less paraflinic and the oils of higher viscosity index are more paraifinic. Herein the expression naphtheuic constituents includes asphalts and mixtures of asphalts and naphthenic oils.

In accordance with this invention, mineral oils are separated into fractions which are respectively more parafiinic and more naphthenic than the originaloil, by subjecting the oil to fractional extraction with wood tar acids which are later removed from the fractions so produced. The wood tar acids have greater solvent power for naphthenlc constituents than for parafiinic constituents of the oil, and the extracting solvent takes up a markedlygreater proportion of naphthenic constituents than it does of paraflinic constituents; and the solution separates from the remainder of the oil and forms a lower layer. The upper layer comprises the remainder of the oil and contains some of the solvent but is markedly richer in parafiinic constituents than is the original oil.

In accordance with this invention, the treatment of the oil with wood tar acids can be a batch operation, and in such case the upper layer may be removed and contacted again with the solvent, such operation being repeated any desired number of times until the oil contained in the final upper layer possesses the desired characteristics. Or, in the practice of this invention, the procedure may be continuous, as by maintaining a countercurrent flow of oil to betreated and extracting solvent, in such case the countercurrent flow of oil and solvent in contact being of such extent or being repeated a sufficient number of times to cause the parafiinic fraction so obtained to possess the desired characteristics.

Wood tar acids which are suitable for the practice of this invention are obtainable in the open market and are usually acids obtained from the tars of harder woods, the tars of softer woods usually containing too little of wood tar acids to justify the recovery thereof from the tar. Ordinarily, but not necessarily, the wood tar acids are recovered from the wood tars by treating the tar with an aqueous solution of caustic soda and then acidulating the resulting aqueous product.

. A specific example of wood tar acids which has; been found to be highly effective in the .which the wax is practice of this invention is a mixture of wood tar acids commercially known as beechwood creosote. Wood tar acids, of which beechwood creosote is an example, are composed chiefly of orthocresol, guaiacol (monomethylcathechol), and cresol; and it is contemplated that, in the practice of this invention, commercial wood-tar acids or the separate ingredients thereof or mixtures of such ingredients may be employed.

In the practice of this invention, the proportion of wood tar acids to oil treated may be varied within a considerable range, for example, one to three parts or more by weight of solvent being employed for each part of oil treated, it being advisable that the aptimum ratio of solvent to'oil be determine by test.

In the practice of this invention, the oil is contacted with the wood tar acid or acids at such temperature as will promote the solution of naphthenic constituents in the solvent employed, and the contacting of the oil and solvent is efiected at, or the mixture is brought to, a temperature which promotes separation of the mixture into distinct layers. Lower temperatures favor the formation of distinct layers and increase the selectivity of the solvent for naphthenic constituents. Advantageous features of the useof wood tar acids are that they are not likely to solidify at temperatures as low as 20 F. and an effective separation into layers occurs at temperatures as high as 100 F. to 160 F. In the treat.- ment of wax-containing oil, the mixture of wood tar acid and oil should at some timebefore' separation possess a temperature at all in liquid state; but the separation of the layers is usually promoted by lowering of the temperature and it ma be made thereafter at a temperature at which a part of the wax is solidified. An advantage of the use of wood tar acids is that with some Mid-Continent oils all steps of the treatment, including separation, may be performed at a temperature at which all of the wax is in llquid state. Another advantageous feature of the use of wood tar acids is that they may be separated completely from oils having an initial boiling point not substantially lower than 450 F., by distillation at temperatures far below temperatures which would tend to decompose either the oil or the solvent. For example, at 10 mm. absolute pressure, the wood tar acids can be separated completely from oil at temperatures not substantially in excess of 425 F. The maximum boiling point of wood tar acids does not ordinarily exceed 225 F. at 10 mm. absolute pressure, and the use of temperatures as high as 425 at 10 mm. absolute pressure effects complete removal of the wood tar acids from the oil and any oil vaporized may be refluxed from the vapors evolved.

In t e practice of this invention, treatment ieo having a final boiling point below the initial boiling point of the solvent, in which case the oil is distilled off of the mixture, leaving the solvent as a residue. Oil constituents having boiling points within the boiling range of the solvent cannot readily be separated rom the solvent by distillation, but only by treatment of the'mixture with aqueous alkaline solutions.

In accordance with this invention, the oil is contacted with a chosen wood tar acid or mixture of wood tar acids at a temperature sufliciently high to effect extensive solution of the naphthenic constituents in solvent but sufliciently low to prevent decomposition, and the oil is allowed to form in two layers at a temperature sufliciently low to promote such layer formation but not so low as to effect solidification of the solvent. The layers ultimately so formed are separated by decantation and the solvent. is removed from both layers. The more paraflinic fraction so formed will possess to a more marked degree than does the original oil those characteristics imparted to oil by parafiinic constituents; and similarly the more naphthenic fraction will possess to a more marked degree than does the original oil those characteristics 0 imparted to oil by naphthenic constituents.

In this manner, the practice of my invention enables the production from Mid-Continent oils and from more naphthenic or asphaltic oils, such as Coastal or California oils, of an oil having a viscosity-gravity constant and a viscosity-temperature index equal to or better than those characteristics of oils obtained from .the Pennsylvania field.

As a specific example, an oil obtained from Mid-Continent mixed base crude oil and having a specific gravity of 0.9236, a Saybolt universal viscosity of 148 seconds at 210 F., and a viscosity-gravity constant of 0.84 was treated in a continuous counter-current flow system with 150% by weight of beechwood creosote at 100 F., and the more paraflinic fraction, after removal of the solvent, had a specific gravity of 0.8944, a Saybolt Universal viscosity of 112 seconds at 210 F. and a'viscosity-gravity constant of 0.812, and, by volume, was 52.4% of the original oil. The more naphthenic fraction produced in that procedure had, after removal of the solvent, a specific gravity of 0.9550, a Saybolt Universal viscosity of 206 seconds at 210 F. and a viscosity-gravityconstant of 0.880.

In the practice of this invention, an extending of continuous counter-flow or a repetition thereof or a repetition of bath ex- .traction treatments results in a further increase of the differences between the characteristics of the original oil and the characteristics of the respective resulting fracv p tion of the naphthenic solvent, e ther by tions. The solvent recovered from the ultimate upper and lower layers, i. e., from.the ultimate parafiinic and naphthenic fraction's,may be repeatedly employed.

The ultimate parafiinic and naphthenic fractions maybe subjected to such further treatment as may be desirable, such as usual refining steps including acid treatment and clay treatment or contact filtration and 'dewaxing, in order to produce finished products. In such case, the finished products obtained from the parafiinicfraction may readily be caused to possess characteristics comparable to or better than the characteristics of Pennsylvania oils.

A further feature of this invention is that in the contacting of the oil with wood tar acids or components thereof, at least some part of the contacting may be efl'ected in the presence of a solvent having greater solvent power for paraflinic constituents than for naphthenic constituents, such simultaneous contacting of the oil with a paraflinic solvent and with a naphthenic solvent being preferably carried out under such conditions that the solvents employed are mutually miscible to only a limited extent. Examples of solvents having selective solvent power for paraflinic constituents are ethane, propane, butane, pentane, petroleum ether, natural gasoline, and 300 F. endpoint Pennsylvania asoline. When using gasoline obtained rom petroleum, the selective solvent power thereof for parafiinic constituents may be improved or insured by preliminarily subjecting the gasoline to extraction with wood tar acids or components thereof" or other solvents having'selective solvent power for naphthenic constituents. of the oil simultaneously with two solvents, the contacting is effected under conditions which insure that at some time in the contacting operation prior to the separation operation all constituents of the mixture will be in liquid phase. Just as lower temperatures favor the formation of separate layers when a solvent having selective solvent power for naphthenic constituents is employed alone, so do lower temperatures favor the formation .of layers between naphthenic and parafiinic solvents'used simultaneously and containing oil constituents in solution.

- In the contacting Procedure wherein paraifinic and naphthenic solvents are simultaneously employed,

and the advantages thereof, are more at length set out in my co-pending application, Serial N 0. 623,483, filed July- 20, 1932. It

is contemplated that naphthenic and parailinic solvents may be simultaneously employed-in either a batch procedure or a continuous procedure. As more ,fully set out in said application, the presence of the parafiin solvent results in more effective operasatisfying the solventpower of the naphthenic solvent for parafiinic constituents or by displacing from the naphthenic solvent, or from the mixture of naphthenic solvent and constituents dissolved thereby, paraffinic constituents which are desired in the paraifinic fraction.

The oil may be brought directly into simulthe naphthenic layer is then contacted with the parafiinic solvent and the resulting lower layer is freed of solvents toprovide the desired naphthenic oil while the resulting upper fraction comprising parafiinic constltuents and solvent and wood tar acid is freed of such solvent and added to the oil passing to the first contacting step. Thus the oil passing to the first contacting step is rendered more parafiinic than the raw charging stock and gives a greater ultimate yield of parafiinic oil, the added paraflinic oil constituting an additional recovery of parafiinlc oil from the naphthenic fraction and assisting in promotin separation, especially in the dividing of big ly napthenic oils.

Moreover, it is contemplated that'the effectiveness of Wood tar acids or components thereof as naphthenic solvents may be increased by mixing with the wood tar acids or components thereof a suitable proportion of sulphur dioxide, and effecting the extraction under conditions which maintain the sulphurdioxide in solution in the naphthenic solvent. The sulphur dioxide has a distinct selectivity for na hthenic constituents and for asphalt an for constituents of higher'molecular weight'but it has limited solvent power for oil constituents and is not soluble in all proportions in oils of high asphalt content as are nitro-aromatic solvents. Other similarv substances are furfural, aniline, and pyridine.

The efiiciency of the operation is substan-.

tially improved by treatment of the oil with the wood tar acids used as naphthenic solvents in the 'resence of a parafiinic solvent. For examp e, a repetition. of the specific example above set forth, using 200% byweight of beechwood creosote and 200% by weight of propane and performing-the contacting and separating at a temperature of 24 F. under a gage pressure in excess of 45' lbs. per square inch, gave a naphthenic fraction, freed of solvents, having a specific gravity of 0.9950,

a Saybolt Universal viscosity of 452'seconds at 210 F., and a viscosity-gravity constant of 0.924. The parafiinic fraction produced as a result of the simultaneous use of the two solvents had substantially the same characteristics as the 'paraffinic fraction produced by 'the use of the beechwood creosote alone,

and it constituted 69.8% of the original oil and was about 33% by volume greater than the paraffinic fraction produced by the use of beechwood creosote alone.

It is contemplated that distillates and residues, refined or unrefined, may be treated in accordance with this invention, this invention being of special importance in the treatment of lubricating oils for the improvement of the characteristics thereof.

It is understood that this invention is not to be limited by any theory of operation expressed nor by any example given, and that it, includes all modifications and variations falling within the appended claims.

claim: 1. In the art of separating mineral oil into its paraflinic and naphthenic constituents, the step comprising extracting the oil with a wood tar acid.

2. In the art of separating mineral oil into its paraflinic and naphthenic constituents, the step comprising extracting the. oil With a mixture of wood tar acids.

3. In the art of separating mineral oil into its parafiinic and naphthenic constituents, the step comprising extracting the oil with beechwood creosote.

4. In the art of separating mineral oil into I its parafiinic and naphthenic constituents, the step comprising extracting the oil with a solvent containing a substantial proportion of one of the substances consisting of guaiacol, creosol, beechwood creosote, and a mixture of two or more thereof. 10(

5. In the art of separating mineral oil into 6. In the production of lubricating oil the 11 step comprising extracting a lubricating oil fraction of petroleum with a solvent containing a wood tar acid.

7 In the production of lubricating oil the step comprising extracting a lubricating oil 11 fraction of Mid-Continent petroleum with a solvent containing a wood tar acid.

8. In a process for separating mineral oil containing parafiinic and naphthenic constituents into fractions respectively more par- 12 aflinic and more naphthenic than the original oil, the step comprising contacting the oil with wood tar acid.

9. In a process for separating mineral oil containing paraflinic and naphthenic constit- 15 uents 'into fractions respectively more paraflinic and more naphthenic than the original oil, the step comprising contacting the oil with beechwood creosote.

10. In the art of refining mineral oil, the 11 having a flash steps comprising contacting mineral oil containing parafiinic and naphthenic hydrocarbons simultaneously with a solvent containing a wood tar acid and with a low-boiling paraffin solvent under conditions causing separation of the mixture into layers, and separating the resulting layers.

11. In a process for separating oil containing paraffinic and naphthenic constituents into fractions respectively more paraifinic and more naphthenic than the original oil, the steps comprising contacting the oil, in the presence of an added liquid having greater solvent power for parafiinic constituents than for naphthenic constituents, with a liquid comprising a wood tar acid.

12. In a process for separating oil containing parafiinic and naphthenic constituents into fractions respectively more paraffinic and more naphthenic than the original 7 oil, the steps comprising contacting the oil, in the presence of an added liquid having greater solvent power for paraffinic constitu-,

ents than for'naphthenic constituents, with bcechwood creosote.

13. In the art of refining mineral oil, the step comprising extracting the oil with a mixture of wood tar acid and sulphur dioxide.

14. In the art of refining mineral oil, the step comprising extracting the oil with a mixture of wood tar acid and one of the gr up comprising sulphur dioxide, pyridine, furfural, analine, and a mixture of two or more thereof.

15. In the art of refining mineral oil, the steps comprising bringing mineral oil having an initial boiling point not substantially below 450 F. into contact with wood tar acid and thereby effecting a solution in the wood tar acid of a portion of the oil richer in naphthenic constituents than is the original oil, separating the solution from the remainder of the oil, and distilling the wood tar acid from the remainder of the oil.

16. In the production of lubricating oil, the steps comprising contacting a residue, point not substantially less than 450 F. and obtained from Mid-Continent petroleum, with wood tar acid, whereby to form two liquid layers, the upper of said layers containing the naphthenic constituents ofthe residue separating the resulting layers, and removing wood'tar acid from the upper layer.

17 In the art of refining mineral oil comprising naphthenic and parafli'nic constituents, the steps comprising contacting the oil with wood tar acid, and contacting the solution of oil constituents in wood tar acid with a solvent having greater solvent power for parafiinic than for naphthenic constituents of the oil. f

18. In the art of refining mineral oil comprising naphthenic and parafiinic' constituents, the steps comprising contacting the oil with a solvent havin greater solvent power for paraflinic than or naphthenic constituents of the oil, and contacting the solvent and the oil constituents dissolved therein with wood tar acid.

19. In the art of refining mineral oil comprising naphthenic and paraflinic constituents, the steps comprising contacting the oil with wood tar acid, contacting the solution of oil constituents in wood tar acid with a solvent having greater solvent power for paraflinic than for naphthenic constituents of the oil, separating the solvent and substances in solution therein from the remainder of the solution of oil constituents in wood tar acid, removing the solvent from said substances in solution therein, and passing the substances to the oil passing to the first-mentioned contacting step.

20. In the art of refining mineral oil comprisin naphthenic and parafiinic constituents, t e steps comprising contacting the oil with wood tar acid,'contacting the solution of oil constituents in wood tar acid with a solvent having greater solvent power for paraffinic than for naphthenic constituentsof the oil, and passing the solvent and oil dissolved therein into the first-mentioned contacting step.

21. In the art of separating mineral oil into its paraflinic and naphthenic constituents, the steps comprising contacting the oil with wood tar acid and thereafter contacting the solution of oil constituents in wood tar acid with a parafiinic solvent of the group comprising any or all of ethane, propane, butane, pentane, petroleum oil, natural gasoline or 300 F. Pennsylvania gasoline.

22. In the art of refining mineral oil, the steps com rising extracting the oil with a mixture 0 wood tar acid and oneof the group comprising sulphur dioxide, furfural, aniline or a mixture of two or more thereof, and simultaneously subjecting the said oil to the action of a paraflim'c solvent of the group comprising any or all of ethane, propane, butane, pentane,- etroleum oil, natural gasoline or 300 F- ennsylvania gasoline.

In testimony whereof, I have signed my name to this specification. I

MALCOLM H. TUTTLE.

DISCLAIMER v l ,9l 2,348.v-Malcolm H. Tattle, New Rochelle; N. .Y. Pnociiss FOR SEPARATION OF)- MINERAL O1L., Patent dated May 30, 1933. 'Disclaimer filed September 17, 1934,.by the asslgnee, Max B. Miller de 00., Im. r Enters this disclaimer to the following claims enumerated below: 7 (a) To claim 1 except in so far as saidclaim covers extracting an oil with ,a wood tar acid other than cresols alone. Y

(b) To eachof clalms 5, 6, and 7 except in so far as said claims cover contacting or extracting-ammeral oil with'a wood tar acid containing guaiacol.

-' Gazette October 16, 1934.}

DISCLAIM-ER 1,912,348.Malcolm H. Tattle, New Rochelle, N. Y. PROCEBQ FOR SEPARATION OF MINERAL OIL. Patent dated May 30, 1933. Disclaimer filed November 23, 1935, by the assignee, Max B, Miller c5: 00,, Inc. Hereby enters this disclaimer of the following parts of the thing patented:

Each of claims 1 and 2 except insofar as said claims cover extracting the oil with a wood tar acid which is peculiar to creosotcs produced from wood tar and which is other than cresylic acid, a cresol, a xylenol, or a higher homolog thereof commonly occurring in substantial amounts in commercial cresylic acid.

[Qficial Gazette December 17,'1935.] 

